“无形学院”具有如下特点:()
A.以优秀科学家为中心
B.立足于自由联合
C.进行通信交流和自由讨论
D.往往是多学科性的
E.为了坚持特定的学术主张
参考答案:A, B, C, D
We could see nothing because the lights suddenly . [ ]
A. went on
B. went over
C. went down
D. went out
高压加热器水位升高原因有哪些?